As used herein, the term “user equipment” (alternatively “UE”) might in some cases refer to mobile devices such as mobile telephones, personal digital assistants, handheld or laptop computers, and similar devices that have telecommunications capabilities. Such a UE might include a device and its associated removable memory module, such as but not limited to a Universal Integrated Circuit Card (UICC) that includes a Subscriber Identity Module (SIM) application, a Universal Subscriber Identity Module (USIM) application, or a Removable User Identity Module (R-UIM) application. Alternatively, such a UE might include the device itself without such a module. In other cases, the term “UE” might refer to devices that have similar capabilities but that are not transportable, such as desktop computers, set-top boxes, or network appliances. The term “UE” can also refer to any hardware or software component that can terminate a communication session for a user. Also, the terms “user equipment,” “UE,” “user agent,” “UA,” “user device,” “mobile device”, and “device” might be used synonymously herein.
As telecommunications technology has evolved, more advanced network access equipment has been introduced that can provide services that were not possible previously. This network access equipment might include systems and devices that are improvements of the equivalent equipment in a traditional wireless telecommunications system. Such advanced or next generation equipment may be included in evolving wireless communications standards, such as long-term evolution (LTE). For example, an LTE system might include an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) node B (eNB), a wireless access point, or a similar component rather than a traditional base station. Any such component will be referred to herein as an eNB, but it should be understood that such a component is not necessarily an eNB. Such a component may also be referred to herein as an access node.
An eNB or similar component that has a small coverage area such as a home may be referred to as a home eNB (HeNB) or a femtocell. The discussion hereinafter may focus on HeNBs, but it should be understood that the embodiments disclosed herein are not necessarily restricted to HeNBs. An access point compliant with the IEEE 802.11 standards may be referred to as a WiFi access point (AP). LTE, WiFi, and other technologies that may be used in wireless communications may be referred to as radio access technologies (RATs).
LTE may be said to correspond to Third Generation Partnership Project (3GPP) Release 8 (Rel-8 or R8) and Release 9 (Rel-9 or R9), and possibly also to releases beyond Release 9, while LTE Advanced (LTE-A) may be said to correspond to Release 10 (Rel-10 or R10) and possibly also to Release 11 (Rel-11 or R11) and other releases beyond Release 10. As used herein, the terms “legacy”, “legacy UE”, and the like might refer to signals, UEs, and/or other entities that comply with LTE Release 10 and/or earlier releases but do not fully comply with releases later than Release 10. The terms “advanced”, “advanced UE”, and the like might refer to signals, UEs, and/or other entities that comply with LTE Release 11 and/or later releases. While the discussion herein deals with LTE systems, the concepts are equally applicable to other wireless systems as well.
In an LTE system, uplink (UL) and downlink (DL) transmissions are organized into one of two duplex modes, frequency division duplex (FDD) mode and time division duplex (TDD) mode. The FDD mode uses paired spectrum where the frequency domain is used to separate the UL and DL transmissions. In TDD systems, on the other hand, unpaired spectrum is used where both UL and DL are transmitted over the same carrier frequency. The UL and DL are separated in the time domain.